Improvement in processes of manufacturing bessemer steel



Unrrnn v sg 'ra'rns PATENT nron.

ROBERT W. HUNT AND AUGUST WENDEL, OF TROY, NEW YORK.

IMPROVEMENT IN PROCESSES OF M'ANUFACTURING BESSEMER STEEL.

Specification forming part of Letters Patent No. 187,386, dated February13, 1877; application filed To all whom it may concern:

Be it known that we, ROBERT W; HUNT and AUGUST WENDEL, of Troy, in thecounty of Rensselaer and State of New York, have invented a new anduseful Improvement in melted pig-iron, or ferro-manganese,spieg'eleisen, or like highly manganized iron, whereby metal containinga high percentage of silicon or sulphur may be employed the bad effectsof hot heats are entirely, avoided, and a saving in fuel, metal, time,and labor is effected,

while the capacity of the works is increased; a smaller percentage ofrecarburizing agent is required, and homogeneoussteel of the highestgrades is readily produced.

The usual mannerof conducting the Bessemer process is to charge theconverter with molten metal from a cupola,air, or blast furnace, inwhich a proper mixture of pig-irons or ores has been previously melted,and then to turn the air-blast onto the metal in the converter, andcontinue the blowing until the flame indicates that conversion iscomplete, after which the converter is turned down, the blast shut ofi',and the proper amount of spiegeleisen or ferro-manganese, in either amelted or solid condition, is added. 7

To make the proper admixture for the blastfurnace or cupola, themanufacturer has to keep on hand a large stock of various brands ofpig-iron and ore, so that he may vary the proportion of each accordingto their several qualities in preparing the charge, and thus obtainmolten metal for the converter process that shall not contain above acertain percentage of silicon, and shall be comparatively free fromsulphur and phosphorus. If the melted iron from the cupola or otherfurnace contains too high a percentage of silicon it will blow or worktoo hot, and cause, if not always the production of bad steel, at leastthe rapid destruction of the ingot-molds and other appliances with whichit comes in contact. In addition to the above difficulties,

June 5, 1876.

the manufacturer has to contend with and make provision for the sulphurimparted to the metal by the fuel used in the cupola or other furnaceemployed to melt the charge.

We will now proceed to describe our invention, so that others skilled inthe art to which it appertains may apply the same.

We first proceed to obtain a charge of melted metal for the converter inthe usual manner, with this exception, that the cupola, blast, or otherfurnace may be charged with such brand or brands of pig-iron orqualities of ores as may be at hand, without regard to the relativeproportions of each, care only being taken to ascertain the percentageof silicon, carbon, &c.,'which will be present in the resulting moltenmetal, as, to a certain extent, the amount of'unmelted pig-iron orspiegeleisen thereafter to beradded in the converter willdepend thereon.

, Knowing the percentage of silicon, &c., present in the charge, thetemperature of the charge, and the pressure and amount of blast tobeblown, all of which are readily ascertained, the operator can readilydetermine to what extent the charge will work or blow too hot, and whatamount of solid or unmelted pig-iron cold, or at any given temperature,must be added to absorb the heat and reduce the temperature to thedesired point. As the proportionate amount of unmelted metal to be usedin the converter depends on the conditions of the charge, as abovestated, and also on the percentage of silicon, manganese, and carboncontained in, and the temperature of, the unmelted metal, we cannot bemore specific, but may here state that we have added as high astwenty-five (25%) per cent. of unmelted metal with a good result. We usethe solid metal either cold or heated, the temperature of the solidmetal being governed by the amount to be introduced and the temperatureof the melted metal in the converter.

Bearing in mind that it will require a larger quantity of solid metal,when heated above the common temperature, to reduce the heat in theconverter to the desired degree, and

'also the converse, that if it is desirable to use as much solid metalas possible in the converter, the pieces should be heated to as high atemperature as possible, short of fusion, and

having determined the quantity, quality, and temperature of the solidmetal to be used in the process, wenext proceed to introduce it into theconverter beforeconversion of the charge in the converter is effected.

We find it most convenient, and therefore prefer, to introduce the solidmetal before the molten metal from the cupola, blast, or other furnaceis run into the converter; but if the quantity of solid metal used isvery large, part of it may be thrown in after the conversion hascommenced and the converter is turned up. We consider that the bestresults are attained by introducing the solid metal during the firstpart of the conversion or blow, though it may be added at any timebefore conversion is complete. From this point on, the usual Bessemerprocess may be followed, excepting that it will be found that a smallerquantity of the recarburizing agents will be required.

The advantages of our improved process are, 1st, that irons containingextremely high percentages of silicon can be used, for the reason thatthe solid metal, even though of the same chemical nature as the meltedmetal, being added in a cold or unmelted state to the charge in theconverter, absorbs in melting such an amount of heat as to keep down theultimate heat of the charge, and thus prevent its blowing too hot, andthis without the use of scrap steel or other converted metal; and

2d, the use of unmelted pig-iron enables the operator to produce bettersteel, or steel of the highest grades and more homogeneous, than by theusual process, forthe reason that in all stages of the conversion, evento the finishing of the blow, the gradual melting of the added metalwill supply silicon and carbon to the charge, and thus prevent the blastfrom oxidizing the metal already almost entirely free from carbon andsilicon.

By substituting spiegeleisen for a portion or the whole of the solidpig-iron, steel of low grades and fine quality, and steel of high gradeequal to the best cast steel can be produced; an additional and powerfulagent, manganese, which prevents oxidation of the metal, is alsoobtained, and the resulting steel will be more free from blow-holes thanthe product of the common process; 3d, there is a saving of fuel to theextent of what would be required to melt that portion of the metal whichis added to the charge in a solid condition, and as the solid metal hasno chance to absorb sulphur, as would be the case if it were meltedbefore introducing it into the converter, a metal containing a higherpercentage of sulphur can be readily used, thus reducin g the necessityfor employing high-priced charcoal iron and expensive steel scrap,valuable for other steel processes.

In the manufacture of tool-steel, it will be found advantageous to blowrather short, which can be easily done, as the change takes place ratherslowly, permitting the blast to be cut oif with safety at the desiredpoint. To make soft steel, the charge should be blown for the full time.

So far as this process is concerned, what we mean herein ,by pig-metalis not only the ordinary products commonly so called, but also thosehighly manganiferous pigs known as spiegeleisen or ferro-manganese.

Having thus described our invention, what we claim, and desire to secureby Letters Patent, is- 4 l. The process of manufacturing Bessemer steelfrom high silicon pig,as herein described, which consists in addingunmelted pig metal to the melted charge in the converter, previous tothe conversion of the charge, substantially as and for the purposespecified.

2. The process of manufacturing Bessemer steel, herein described, whichconsists in adding portions of pig-iron and spiegeleisen, orferro-mangauese, in a solid or unmelted condition to the charge in theconverter previous to the conversion of the charge, substantially as andfor the purpose speclfied.

In testimony whereof we, the said ROBERT W. HUNTand AUGUST WENDEL, havehereunto set our hands.

ROBERT W. HUNT. AUGUST WENDEL. Witnesses:

P. HARRY MITCHELL, LEMUEL HURLBUT.

